Anatomy and Physiology: Levels of Organization and Body Planes

Levels of organization (lowest to highest)

Atom, Molecule, Cell, Organ, Organ System, Organism

Atom

Smallest unit of matter.

Molecule

Two or more atoms bonded together.

Cell

Smallest living unit of the body.

Organ

A structure made of different tissues working together.

Organ system

A group of organs working together to perform a major function.

Organism

The complete human body.

First living level of organization

Cell

Anatomical plane

An imaginary flat surface that divides the body into sections.

Sagittal plane

Divides the body into right and left sections.

Midsagittal plane

Divides the body into equal right and left halves.

Coronal (frontal) plane

Divides the body into anterior (front) and posterior (back) sections.

Transverse plane

Divides the body into superior (upper) and inferior (lower) sections.

Plane used for top and bottom halves

Transverse plane

Plane used for front and back halves

Coronal plane

Plane used for right and left halves

Sagittal plane

Abdominal divisions

Methods used to describe locations of pain, injury, or organs in the abdomen.

Two abdominal division systems

Four quadrant system and nine region system

Four quadrant system

Abdominal division using two planes intersecting at the umbilicus.

Umbilicus

Navel; center of the abdomen.

Right upper quadrant (RUQ)

Upper right abdominal quadrant.

Left upper quadrant (LUQ)

Upper left abdominal quadrant.

Right lower quadrant (RLQ)

Lower right abdominal quadrant.

Left lower quadrant (LLQ)

Lower left abdominal quadrant.

Gallbladder location

Right upper quadrant (RUQ).

Appendix location

Right lower quadrant (RLQ).

Spleen location

Left upper quadrant (LUQ).

Nine abdominal regions system

Abdominal division method using nine equal regions.

Number of abdominal regions

Nine.

Center of the nine regions

Umbilical region.

Planes used in nine-region system

Two parasagittal planes, transpyloric plane, transtubercular plane.

Transpyloric plane

Superior transverse plane used in the nine-region system.

Transtubercular plane

Inferior transverse plane used in the nine-region system.

Right hypochondriac region

Upper right abdominal region lateral to the epigastric region.

Epigastric region

Upper middle region above the stomach.

Left hypochondriac region

Upper left abdominal region lateral to the epigastric region.

Right lumbar region

Middle right abdominal region lateral to the umbilicus.

Umbilical region

Middle center abdominal region.

Left lumbar region

Middle left abdominal region lateral to the umbilicus.

Right iliac (inguinal) region

Lower right abdominal region.

Hypogastric region

Lower middle region below the stomach.

Left iliac (inguinal) region

Lower left abdominal region.

Epigastric meaning

Above the stomach.

Hypogastric meaning

Below the stomach.

Hypochondriac meaning

Superior and lateral to the stomach.

Lumbar meaning

Region of the low back; lateral to the umbilicus.

Iliac (inguinal) meaning

Lower lateral abdominal regions.

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